Loongson-3 series CPUs include 4-core 3A, 8-core 3B, 16-core 3C as well as other series CPUs later developed.
Loongson-3 is a general-purpose multi-core CPU with MIPS (Microprocessor without Interlocked Pipeline Stages) architecture, functioning similar to Intel or AMD (Advanced Micro Devices) X86 architectures while enjoying unique advantages in energy conservation and safety. Although Loongson-3 CPU slightly lags behind the X86 CPU in performance, it can be a replacement to the X86 CPU in most cases.
Although Loongson-3A and Loongson-3B CPUs have been made public, the critical issue regarding how the Loongson CPU can work most efficiently (i.e. to find north and south bridge chipsets and peripherals which could match with the Loongson CPU and function well) remains unresolved prior to the present invention.
Even though a type of chipsets can be selected to match the Loongson CPU in debugging, at a debugging failure, it is difficult to identify whether the bugs come from the Loongson CPU or the incompatibility between the CPU and the chipsets. If the former is the cause, the bugs of the CPU can be modified without abandoning the selected chipsets; if the later is the cause, a new type of chipsets need to be selected. However, the current debug method based on wild speculation and spontaneous experiments can hardly identify the real cause. Therefore, it's imperative to find a flexible debug method that can accurately identify the source of the failure in debugging.
When bugs are found in the Loongson CPU, especially on the Hyper Transport (HT) bus (as shown in FIG. 1) in current debug method, the only solution available is to modify the design of the Loongson CPU, and the debug can not resume until the Loongson CPU with a modified design is welded. On the other hand, power up/down sequences and the configuration of signal lines between the Loongson CPU and chipsets can't be determined until the adaptive chipsets are found.
As shown in FIG. 1, according to the current debug method, a type of chipsets matches with a type of motherboard. It usually takes at least two months to design and manufacture a motherboard. If adding the debug time, it takes at least six months to test a selected motherboard, which is long and costly. In addition, because the current debug method cannot debug different types of chipsets on one motherboard simultaneously, it requires different types of motherboards.
FPGA (Field Programmable Gate Array) is used in flexible field programming. FPGA may also repeatedly modify the code, simulate common 10 interfaces (for example, HT bus, PCIE bus and SerDes), flexibly change clock frequencies and adjust the signal level as well as on-line signal detection.